Movement stops after a few ticks

[chaz76vette]

Hello! This is my first post. Newbie to watch repairing but I have a good mechanical background.

Looking for likely causes of the problem described below:

Bulova mechanical watch, 1964 (M4), AC11 movement (hand winding)

Watch will not tick consistently. At best it will move for a few seconds and stop. The only way to get it started is lightly tapping or turning upside down, then it will move for a few seconds and stop again.  When moving, the seconds hand sometimes jumps around (skips forward or backward), but the hand itself appears attached fine, meaning it is not loose; the skipping appears to happen in the movement. 

Also it will not wind. The crown will turn in reverse (freewheeling) but will not turn forward (winding).  It’s possible to set the time no problem, so at least some of the works are free. 

I took the movement out and blasted it with air, and there’s no obvious obstruction. When the watch does move briefly, the balance wheel looks a little loose? But not sure if it’s supposed to look that way. While the movement was out, I noticed it also moves/ticks when I blow on it.   

Any ideas as to where I should start would be helpful - does this sound like an issue with the main spring, or an obstruction, etc?

 

thanks!

[Graziano]

Hi there , firstly I hope you are only using very gentle puffs of air otherwise you could damage the hairspring that is attached to the balance wheel ,which by as you describe may be shot ,Sounds like the mainspring has a problem ,and a good service will do wonders .How much experience do you have pulling apart a watch movement ? .If you are just starting may I suggest to you have a look at Mark Lovic's watch repair lessons  www.watchrepairlessons.com/.The course will provide information on fault finding ,servicing and what tools you need to get started .You can search online for a donor movement or parts . There is a wealth of information on this forum and I'm sure someone else will chime in soon . Hope this helps you  .nice watch by the way

Edited March 4, 2020 by Graziano

[Nucejoe]

Sounds like a broken pivot at cock side. 

Gently lift one side of balance wheel while keeping an eye on said pivot( side view) , an observable side shake of the pivot is a sure indication of a broken pivot or at very extreme case a  broken jewel.  posting a magnified close up video of checking this ,  helps.

That it dose not wind, could be that mainspring is fully wound, we tend to wind a non runner thinking more power may make it run.  

Will you explain  more, " the seconds hand skips forward or back word "  

[chaz76vette]

Thank you both for the replies!

11 hours ago, Graziano said:

If you are just starting may I suggest to you have a look at Mark Lovic's watch repair lessons  www.watchrepairlessons.com/.

I will check that out, thank you (and anyone else who can recommend good books/resources.  I am seeking to do these repairs myself; not take it to a shop.

9 hours ago, Nucejoe said:

Sounds like a broken pivot at cock side. 

Gently lift one side of balance wheel while keeping an eye on said pivot( side view) , an observable side shake of the pivot is a sure indication of a broken pivot or at very extreme case a  broken jewel.  posting a magnified close up video of checking this ,  helps.

That it dose not wind, could be that mainspring is fully wound, we tend to wind a non runner thinking more power may make it run.  

Will you explain  more, " the seconds hand skips forward or back word "  

I will try that and attempt to post video.  The balance wheel looks loose to me (it teeters and wobbles) but it does spin when the movement is ticking.  

Regarding the seconds hand: when it's moving it sometimes skips a couple "seconds" forward or backward, rather than making a smooth sweep.  But I think this may just be because I was tapping the case to try and get it to work.  The fact that it tends to jump forward AND backward leads me to believe there may be an issue, but not sure until I can get it to move without tapping on it.

[Nucejoe]

3 minutes ago, chaz76vette said:

Thank you both for the replies!

I will check that out, thank you (and anyone else who can recommend good books/resources.  I am seeking to do these repairs myself; not take it to a shop.

I will try that and attempt to post video.  The balance wheel looks loose to me (it teeters and wobbles) but it does spin when the movement is ticking.  

Regarding the seconds hand: when it's moving it sometimes skips a couple "seconds" forward or backward, rather than making a smooth sweep.  But I think this may just be because I was tapping the case to try and get it to work.  The fact that it tends to jump forward AND backward leads me to believe there may be an issue, but not sure until I can get it to move without tapping on it.

Skipping a few seconds,  shows pallets let escapement of several teeth in one go, which indicates broken escape or fork arbour of misaligned pallet jewels, etc.

You can just take balance and cock out, then check the fork and decide if you want to disconnect the balance complete from the cock.

Close up pix would do, no longer need video.

[MrRoundel]

Is it possible that the "skips" are what is referred to as flutter, with the indirect center seconds? I ask because I was just inquiring about a V&C with the indirect center seconds hand. My research had brought me to a lot of descriptions of this hand flutter.

Along the same lines, is it possible that the tension spring on the ICS (Indirect Center Seconds) is too tight? I'm just doing what at least I call "thinking" out loud. Good luck to the OP.